Catalytic conversion of hydrocarbons



Patented Nov. 9, 1948 oaraurrc CONVERSION ornrnaocannons GeorgeAlexander Mills, Ridley Park, Pa., assignor .i I i to Houdry ProcessCorporation, Wilmington, Del., a corporation of Delaware No Drawing.Application October 19, 1944, Serial No. 559,483

6 Claims. (01. 1 96--52) The present invention relates generally to theart the catalytic treatment of hydrocarbons and specifically to thecatalytic cracking of such materials.

The application of cracking processes to crude oils, petroleumdistillates and other hydrocarbon fractions has increased the amount ofcommercially valuable products from such sources. Various inventionsconcerning the apparatus and methods of conducting the fundamentalprocess are known but only a small number of agents capable ofaccelerating the desired changes have been found. industrially, theprincipal catalysts for cracking are certain types of activated naturalclays and certain synthetic silica-alumina gel composites.

An object of the present invention is to produce fuels which improve theefficiency or power of oil engines. Another object is to crack thehydrocarbon material so that, in addition to gasoline of high anti-knockproperties, the process yields by-products that can be commerciallyutilized.

Another object is to convert hydrocarbon materials into otherhydrocarbon materials more valuable in commerce by contact, undercracking conditions, with a novel catalyst. Further objects andadvantages will be apparent in the following description and claims. a

A preferred form of this invention is a catalytic treatment in which thehydrocarbon material to be cracked is contacted with a mass consistingessentially of colloidal silica-mania at a temperature above 700 F.under conversion conditions.

A principal application of this invention is the cracking to gasolineand valuable gaseous prodnets, of hydrocarbon materials boilingessentially higher than gasoline. The product recovered from thecontacting operation may be separated into a, gaseous fraction and asynthetic crude. The synthetic crude yields, on distillation, a stablegasoline of high octane and blendin value for I internal combustionmotors either of the automotive or aviation type. The gaseous fractioncan be further processed by well-knownmethods oi alkylation orpolymerization to yield additional quantities of premium motor fuel.Selected portions of the gas may be further treated to form highlyunsaturated hydrocarbons useful in the production of syntheticelastomers. The portion of the synthetic crude remaining after theremoval of gasoline may be recycled to produce more gasoline orprocessed to yield useful products such as furnace oil. cleanersnaphtha, paint solvents or thinners, chemical intermediates and thelike. However, the invention is not limited by the type of charge orproduct and may be applied to the improvement of the stability, octanenumber and/or lead response of gasoline by treatment under crackingconditions; to the reforming of naphthas resulting in an increasedoctane number and lead response and lowered boiling ranges; to theproduction of fuels for oil engines not of the gasoline type; and alsoto the cracking of hydrocarbon gases.

Contact masses useful for catalytically cracking hydrocarbon materialsare rare. Because of the present lack of'exact knowledge concerning theactual mechanism of catalysis, the properties upon which catalyticactivity depends are not known, nor has analogy with compounds showingcatalytic activity proven valid in many cases. Exact predictionsconcerning the cracking activity of an untested combination of chemicalcompounds are impossible since certain combinations have catalyticproperties possessed by neither component and the art has not reachedthe stage where the effect of combining various chemical compounds canbe anticipated. Therefore untested compounds or mixtures of compoundscan. be regarded only as possible catalysts. Such conclusions must beexperimentally verified.

One of the objects of this invention is t set forth an improved methodof preparing a on r tact mass consisting essentially of colloidal sinceurania as'described below. It is within. the scope of the invention touse any appropriate methods of preparation such as grinding or mullingmixtures of colloidal urania and colloidal silica prepared separately,reaction in the liquid or vapor state of organic compounds of uraniumand silicon, impregnation of a gel of one component with the solution ofa salt of the other component with subsequent decomposition of the salt,intimate mixture of hydrogels prepared separately, deposition on acarrier, and the like. In all cases, a method of manufacture is usedwhich produces a catalyst having a high specific surface, since theeffectiveness of the contact mass depends on the surface. Furthermore,any method is successful only when the various components comprising thesurface active mass are uniformly mixed. It is in the sense of anintimate colloidal mixture that the term "silica-uranla is used in thisinvention. The terms, silica, urania or sllica-urania, denote colloidalmasses before or after calcination. Calcination is used in the sense Ofany heat treatment at a temperature above 400 F. Theories of thedistinction between colloidal hydrous oxides, hydroxides, hydratedoxides and the like do not limit this invention,

. 3 nor is it limited by theories of the composition of the oxidesproduced on calcination.

In a preferred form of this invention, a solution of a silicate and asolution containing a compound of uranium are brought into rapidintimate contact by a mechanical mixing device under conditions wherebythe hydrogels of silica and urania are concurrently formed. A thirdsolution containing acids, alkaline compounds or neutral salts may beadded simultaneously or subsequently to the solutions to adjust the pHof the final mixture, aid in pH adjustment by builer action, or have adesired effect on the structure of the resulting hydrogel. Since thecatalyst may be prepared in any form which yields aggregates ofcoiloidsize, solutions of the reagents may be are milder (loweredtemperature, higher rate tions that would cause considerable cracking ofa carbon mixtures containing'compounds boiling higher than gas oil arecracked to give excellent yields of motor fuel when the crackingconditions and/or lower cracking pressure).,.than those used tgeated soasto produce hydrosols, gels, gelatinous precipitates and the like aswell as hydrogels. In general. the pH shown by resulting coagulum is.between 2 and 11.5 but it is preferred to fix conditions so as to havean acid reaction (i. e., a pH of less than 7) shown by the resultinggels of silica and urania. Syneresis liquors may then be removed fromthe'hydrogel, the gel dried, washed to remove salts, treated to removeadsorbed materials detrimental to the catalyst, principally alkalis,again dried, ground and formed by grinding, extrusion, pelleting ormolding into sconvenient shapes. The sequence of operations describedabove is merely preferred and the invention is not limited by anyspecific permutation of processing operations. The finished calcinedcatalyst consists essentially of about 5 to 30% uraniaand about 95 to70% silica. It is within the scope to add small amounts (not over 1%) ofother oxides for promoter action. Thus the activity of the catalyst maybe enhanced by the addition, in the original solutions or at any step inthe preparation of the catalyst, of 1% or less of compounds of elementshaving refractory oxides such as. beryllium, magnesium, zinc, strontium.barium. aluminum, titanium, zirconium, cerium. and thorium. Theoreticaldefinitions of promoter action shall not limit the use of these minorcomponents since the sole criterion of their effectiveness in terms ofthis invention is improvement in performance The conditions used in theprocess employing the prepared mass consisting essentially of colloidalsilica-urania are adjusted to the type of hydrocarbon material to beconverted and the degree of cracking desired. It has been iound thattemperatures in excess of 700 F. and below 1200 F. are suitable. Ingeneral, the space rate used will lie between 0.25 (0.25 volume ofcharge liquid per 1 volume of catalyst per hour) and 5. Rates in themiddle portion of this range, as for instance 0.5 to 2.5, are preferredwhen gas oils and the like are cracked and a substantial quantity ofgasoline is desired. Higher rates such as 2.0 to 5.0 are generallychosen when the operation for gas oil. Such hydrocarbon mixtures are ofthe type produced from the residuums of crude oil distillation by suchmethods as tar separator distillation, coking, dewaxing; vacuumdistillation, and deasphaltlzing. Desaltingand other processes whichremove inorganic impurities may be used inconjunction with any of thesemethods. Any of the charges mentioned above may contain asoline.

Various specific embodiments of this invention A solution was preparedby diluting1'C5 by weight of a commercial silicate (N-brand) with 163parts by weight oi water. Into this solution was poured. with agitation,a second solution containing 1 part by weight of UO:(NO3) 2.81120 and1'7 parts by weight of (NHOzSO4 solution (having a specific gravity of1.41) diluted with 92.5 parts by weight of water. A 'coagulum formedupon the addition or the second solution. The entire mixture had a pHoi' 10.0. The gel was filtered and dried in ovens at 200 to 210 F. Thedried gel was washed with distilled water, then with a solutioncontaining ammonium chloride and suillcient ammonium hydroxide to renderthe solution basic, finally with distilled water, and then dried inovens at 200 to 210 F. The dry gel was ground 3 hours in a ball mill.The ground powder (1 part .by weight) was mixed with 1.17

parts by weight or water and formed as pellets in a die plate. Thetheoretical composition of the material at this point was 90% by weightcalculated as $10: and 10% by weight calculated as UaOs.

A portion of the material so prepared was heat treated for 5 hours at atemperature of 1400 F. with a mixture of 6.5% steam and 93.5% air. Someof the heat treated pellets were employed for the cracking of a gas oilessentially in accordance with the method described in detail in the"National Petroleum News" 36, No. 31, R-537-38.

(Standard conditions are a space rate of 1.5.

' atmospheric pressure. and the temperature of the is that of reforminga naphtha. while lower rates.

such as 0.25 to 1.5, are desirable for treating cracked gasoline inorder to'improve its quality. The vapor pressure of the hydrocarbonmaterial during the period of contact with the active mass may yaryconsiderably depending on the charge and the extent and type ofconversion desired.

The material used as a charge to the process and catalyst describedabove is varied depending on the prevailing economics. Gas oil anddistillates of similar boiling range are preferred when the end productis aviation gasoline. Distillates oi a boiling range lower than gas oil.are converted to superior motor fuels by a treatment undercondircontact mass at 800 F.) The synthetic crude so produced was fractionatedand yielded 6.9 volume per cent .of gasoline based on the charge.

Example 11 A solution was prepared by diluting 20.8 parts by weight of acommercial silicate (N-brand) with 9.1 parts by weight of water. Asecond solution was prepared by dissolving 1 part by weight of uranylacetate in 197 parts by weight '0! water and adding 4.1 parts by weightor acetic acid. The two solutions were poured together.

' containing ammonium chloride and finally with distilled water. The gelwas again dried and formed in a pelleting machine of the pressure type.The resulting pellets were heat treated at a temperature of 1400 F. forhours in a mixture of 5% steam and 95% air.

The catalyst thus prepared was employed for the cracking of a gas oil asdescribed in Example I, and produced 19.1 volume per cent of gasolinebased on the charge. The gasoline made had a density of 0.7709 andcontained volume per cent of aromatics (indication of a high antiknockvalue). The gas made during the cracking run showed a ratio of 8 volumesof isobutane to 1 volume of n-butane, again indicating a high antiknockvalue for the gasoline produced.

I claim as my invention:

1. In the production of high octane gasoline from normally liquidhydrocarbon material by catalytic conversion processes of the type inwhich no hydrogen is introduced to the conversion zone. the improvementwhich comprises ei'-. fecting said conversion by contacting saidhydrocarbon material under cracking conditions including temperaturesbetween 700 and 1200 F. with a surface active contact mass consistingessentially of silica and urania, said mass having been prepared bycoprecipitation of colloidal silica and urania in an acid menstruum.

2. In the production of high octane gasoline,

the process which comprises contacting normally liquid hydrocarbonmaterial under cracking conditions with a surface active mass consistingessentially of silica and urania, said mass having been prepared bycoprecipltation of colloidal silica and urania in an acid menstruum.

3. The process of claim 2 in which said surface active contact masscontains more than 5% of urania.

4. The process of claim 2 in which said surface active mass containsbetween 5 and of urania.

5. The process which comprises cracking normally liquid hydrocarbonmaterial comprising hydrocarbons boiling above gasoline to formsubstantial amounts of high octane gasoline from said hydrocarbonsboiling above gasoline by contacting said hydrocarbon material undercracking 6 conditions with a surface active mass consisting essentiallyof silica and urania, said mass having been prepared by coprecipitationof colloidal silica and urania in an acid menstruum.

6. The process which comprises cracking hydrocarbon material boilingabove gasoline to form substantial amounts of high octane gasoline bycontacting said hydrocarbon material under cracking conditions with asurface active mass consisting essentially of silica and between 5 to 30percent of urania, said mass having been prepared by coprecipitatingcolloidal aggregates of silica and urania from solutions containingsoluble compounds of uranium and silicon under such conditions as toproduce an acid reaction in the menstruum containing said aggregates,separating said colloidal aggregates from said menstruum, treating theseparated colloidal aggregates so as to remove adsorbed materialsdetrimental to the catalyst and heat treating the purified colloidalaggregates at a temperature in,

excess of 900 F.

GEORGE ALEXANDER MILLS. REFERENCES orrEn The following references are ofrecord in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,657,753 Jaeger et al Jan. 31,1928 1,870,357 Dierichs Aug. 9, 1932 1,986,557 Connolly et a1. Jan, 1,1935 2.258111 Engel Oct. 7, 1931 2,268,109 Connolly Dec. 30, 19412,278,677 Stahly'et al Y Apr. 7, 1942 2,291,885 Egiofl Aug. 4, 19422,331,338 Michael et a1. Oct. 12, 1943 2,343,192 Kuhn Feb. 29, 19442,356,576 Free et al Aug. 22, 1944 2,370,541 James Feb. 27, 19452,372,165 Arveson Mar. 20, 1945 2,381,825 Lee Aug. 7, 1945 FOREIGNPATENTS Number Country Date Great Britain Apr. 24, 1939

